Is the IMX 571 sensor a good fit for 150p

[poogle]

Hi all!

I've finally decided to upgrade my imaging setup. I'm currently using a StarlightXpress H-18 CCD. At first my plan was to get an ASI294mm, but now I'm leaning towards getting a camera with the IMX571-sensor instead, probably the Omegon veTEC 571 mono with the same price tag as the ASI294mm.

The reason is mainly that I suspect that I will need to put more effort into processing (which I'm not very fond of) withe the 294.

My question is: Will the sensor be a good fit for my Skywatcher Explorer 150p (FL 750mm), with a Baader CC MKII, StarlightXpress filter wheel with 36mm narrowband filters and a Moonlite focuser?

The setup will be located under Bortle 4 skies.

Cheers 

[ONIKKINEN]

I think the 571 is not just a good fit, but possibly the best fit for just about any scope.

Cant see how you would be disappointed with it!

[tomato]

I also think you won't be disappointed with a IMX 571 sensor. Based on posts on SGL , it has become a very popular camera since it's introduction.

[AstroMuni]

Are there any vendors in UK who sell the 571 cameras?

[tomato]

IMX 571 based astro cameras are available from a number of vendors in the UK, examples available from UK vendors are  ZWO ASI 2600,  QHY268 and the Altair Hypercam 26. The cheapest variants however, such as the RisingCam, are as far as I know, only available direct from China. This thread documents one experience of going down that route.

 

[poogle]

Thanks for the input!

Sounds like a great sensor, how about with regards to my scope (pixel size, under/over sampling and vignetting). Also, will I need an IR/UV filter at the same time as my narrowband filters? The camera glass is AR coated.

[ONIKKINEN]

12 minutes ago, poogle said:

Thanks for the input!

Sounds like a great sensor, how about with regards to my scope (pixel size, under/over sampling and vignetting). Also, will I need an IR/UV filter at the same time as my narrowband filters? The camera glass is AR coated.

1" Per pixel that you would get with that setup is probably a bit optimistic, but if you Bin x2 youll probably be close to what seeing will give you on most nights. But also depends on the MPCC really how well it performs on what kind of workable resolution you get out of it. If its a "soft" corrector like my previous TS- Maxfield 0.95x was you may need to Bin x3. I would say dont worry about it too much, its going to be great with your scope.

[Clarkey]

45 minutes ago, poogle said:

Also, will I need an IR/UV filter at the same time as my narrowband filters?

No. The IR/UV wavelengths are removed by the NB filters. You only need this for normal OSC imaging.

[Adam J]

On 04/08/2022 at 15:17, poogle said:

Hi all!

I've finally decided to upgrade my imaging setup. I'm currently using a StarlightXpress H-18 CCD. At first my plan was to get an ASI294mm, but now I'm leaning towards getting a camera with the IMX571-sensor instead, probably the Omegon veTEC 571 mono with the same price tag as the ASI294mm.

The reason is mainly that I suspect that I will need to put more effort into processing (which I'm not very fond of) withe the 294.

My question is: Will the sensor be a good fit for my Skywatcher Explorer 150p (FL 750mm), with a Baader CC MKII, StarlightXpress filter wheel with 36mm narrowband filters and a Moonlite focuser?

The setup will be located under Bortle 4 skies.

Cheers 

It's a good camera but I actually think that the larger pixels and smaller sensor of the 294 may be a better bet in this case. My experience is that you will struggle to get good correction into the corners of a mono APSC sensor with small pixels on a F5 Newtonian and the baader corrector. You may do better with a 4 element corrector (I only just managed it with a ASI1600mm pro). I would also worry about vignetting on the 150P unless you have upgraded it to a larger secondary mirror as I believe that the secondary on the 150P is smaller than the 150pds and the one on the 150PDS is arguably already on the small side. 

Adam 

Edited August 18, 2022 by Adam J

[FredNurk]

I am using the Altair 26c and the Touptek mono 571 cameras with 10 inch f5 celestron newtonian and a non Quatro f5 12 inch  Skywatcher Newtonian. Both have a generic coma corrector from FLO and the results are very promising and a quantum leap from the zwo 294. Lots of dynamic range, no amp glow and super easy to process. I will be buying the new Starizona corrector for both fairly soon... ouch.

The bigger issue for both scopes was that the flop in the original focusers caused tilt issues that were uncorrectable. I moved to a baader steel trak and the problem disappeared. 

 

[Adam J]

2 hours ago, FredNurk said:

I am using the Altair 26c and the Touptek mono 571 cameras with 10 inch f5 celestron newtonian and a non Quatro f5 12 inch  Skywatcher Newtonian. Both have a generic coma corrector from FLO and the results are very promising and a quantum leap from the zwo 294. Lots of dynamic range, no amp glow and super easy to process. I will be buying the new Starizona corrector for both fairly soon... ouch.

The bigger issue for both scopes was that the flop in the original focusers caused tilt issues that were uncorrectable. I moved to a baader steel trak and the problem disappeared. 

 

Both of those are likely to have a larger secondary relatively than the 150p though. 

[FredNurk]

150 has a 47mm secondary and my N10 has 55mm and the 300 skywatcher has 70mm . I have minimal fall off on the N10 . From memory the diagonal on the APS-c is about 27mm... I wonder if flats alone could remedy any resulting vignetting.

Ross

[vlaiv]

25 minutes ago, FredNurk said:

150 has a 47mm secondary and my N10 has 55mm and the 300 skywatcher has 70mm . I have minimal fall off on the N10 . From memory the diagonal on the APS-c is about 27mm... I wonder if flats alone could remedy any resulting vignetting.

Ross

Flats will work, but problem is not with flats as much as light loss itself. If you get significant vignetting - you'll get much worse SNR in corners.

Say you have 50% vignetting. That is like you exposed corners only for half of total time - SNR will be only ~70% of center.

Here is quick diagram of vignetting based on specs that I managed to find online:

This is for 150mm F/5 newtonian with 185mm distance between Focal plane and diagonal. I figured following: DSLR can reach focus on 150P, so we have at least 90mm from optical axis to tube edge (tube diameter is 180mm), then we have at least 50mm of focuser and 44mm of flange focal distance for DSLR giving total of 184mm. I used 185.

At edge of the field - magnitude loss is 0.3mag which translates to about 75% illumination. Which is ok.

I'd be more worried about field definition and vignetting depending on coma corrector.

Here are some interesting examples of how CCs perform on 10" newtonian on 4/3 sensor:

https://www.astrofotoblog.eu/?p=856

 

 

[poogle]

Thank guys for all your input, very insightful indeed!

I went ahead and bought the Omegon veTEC 571 mono last week and managed to test it once, under quite bad conditions with high clouds. Attached is a single frame with only STF applied in PixInsight. I'm certainly no pro, but the vignetting seems manageable, I don't know about tilt though?

The coma seems a bit worse than before, so might have to get a better coma corrector, will have to measure the remaining distance of the focus tube though since some of the better CCs are quite long.

[poogle]

Finally had a chance to image for an hour with decent conditions. Collimated my scope last week, and the star shapes look way better than in the last image.

Here is the result with perfect framing as you can see  

5x300s HA, 5x300 OIII. GAIN: 0 in SGP, but the FITS file says 100, so not really sure. Binning 2x2.

Had to crop it somewhat since I got some strange effects in one of the corners in my OIII stack, might need new flats. Just used the AutoIntegrate-script in PixInsight to do the processing for me

As a comparison below is my last try in 2018 using my old CCD, think it was around 2-3 hours total integration on that one.

[vlaiv]

38 minutes ago, poogle said:

Here is the result with perfect framing as you can see

That is just artistic license

There is a lot of SNR in that image. You could really sharpen it up without introducing too much noise.

Maybe even consider doing starless processing.

Separate nebulosity and stars with starnet++ and process separately. Image would benefit from taming the stars. It is busy star field and since image goes deep - there is plenty of stars.

When stretching to show faint nebulosity - stars also get stretched and show much more - that makes image even "busier".

[Adam J]

On 20/08/2022 at 16:13, poogle said:

Thank guys for all your input, very insightful indeed!

I went ahead and bought the Omegon veTEC 571 mono last week and managed to test it once, under quite bad conditions with high clouds. Attached is a single frame with only STF applied in PixInsight. I'm certainly no pro, but the vignetting seems manageable, I don't know about tilt though?

The coma seems a bit worse than before, so might have to get a better coma corrector, will have to measure the remaining distance of the focus tube though since some of the better CCs are quite long.

You mention a better coma corrector, not entiarly sure that its all not still colimation or flex in the tube due to the weight of the camera, but the other thing I see in the above image is evidence of primary mirror pinching. Might be an idea to slightly back off the primary mirror clips and see if that helps you.

If the ES corrector will work then its a great option if not then another long barrel 4 element ED design, there are a few clones on the SW Quatro corrector about.

Adam

[poogle]

20 hours ago, Adam J said:

You mention a better coma corrector, not entiarly sure that its all not still colimation or flex in the tube due to the weight of the camera, but the other thing I see in the above image is evidence of primary mirror pinching. Might be an idea to slightly back off the primary mirror clips and see if that helps you.

If the ES corrector will work then its a great option if not then another long barrel 4 element ED design, there are a few clones on the SW Quatro corrector about.

Adam

Thanks Adam, how did you notice the primary mirror pinch? I can understand it in the post made on the 20th of August where the star shapes are off, but in the image from yesterday I cannot really see any odd shapes?

[Adam J]

18 hours ago, poogle said:

Thanks Adam, how did you notice the primary mirror pinch? I can understand it in the post made on the 20th of August where the star shapes are off, but in the image from yesterday I cannot really see any odd shapes?

Can't zoom in sufficiently on my phone right now. It's easier to see in the less processed image earlier yes, but hints of it in the later images you posted. Slightly triangular stars with flairing. Although it could also be the focus tube in the light path. Hard to diagnose the difference between the two myself. You would need to look down the tube.